U.S. Pat. Nos. 6,874,647 and 7,147,118 disclose a closure, a package and a method of assembling and filling a package that are particularly well adapted for high-temperature applications. Such high-temperature applications include, for example, applications in which the container is filled with product while the product is hot, such as so-called hot fill and asceptic fill applications. High-temperature applications also include applications in which the filled package is subjected to pasteurization or retort after filling. During retort applications, for example, the filled package can be subjected to a temperature of 265° F. for 15 minutes. High-temperature applications also can occur when a package is filled with a carbonated beverage and subjected to storage under high-temperature conditions, in which the internal pressure within the container can increase dramatically. In all of such high-temperature situations, the container closure is subjected to elevated internal pressure, which tends to distort or dome the closure and interrupt the seal between the closure and the container neck finish.
The noted patents disclose a plastic closure that includes a plastic closure shell having a base wall with a central opening and a skirt with at least one internal thread segment or at least one internal bead for securing the closure to a container neck finish. A plastic disk is retained within the shell. The disk includes a plurality of axially extending spacer elements around the disk to engage the undersurface of the shell base wall and space the disk from the base wall of the shell, and angularly spaced fingers extending from the disk through a central opening in the shell base wall to retain the disk within the shell. A resilient liner may be disposed on an underside of the disk for sealing engagement with the container neck finish.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A plastic closure in accordance with one aspect of the present disclosure includes a plastic closure shell having a base wall with a central opening and a skirt for securing the closure to a container neck finish. A plastic disk includes angularly spaced fingers extending into the central opening of the shell base wall and external beads on the fingers for engaging an inner periphery of the central opening to retain the disk within the shell. The beads have flat undersurfaces and the inner periphery of the central opening has a ledge with a conical surface engaged by the beads. Any doming that occurs in the disk and/or the closure shell base wall increases the surface contact between the finger beads and the opposing surface of the ledge so that removal of the shell from a container neck finish will simultaneously lift and remove the disk from the neck finish without having the beads snap through the central opening in the shell so that the shell is removed while the disk is retained on the neck finish.